1. Field of the Invention
The present invention generally relates to a device for forming images on a large surface, and more particularly to such a device for use in displaying images on a spherical surface.
2. Background Discussion
Current simulators, in particular aircraft simulators, comprise a sphere, on which are projected synthesized and/or prerecorded images. Such simulators have, approximately at the center thereof, a booth in which the users sit, the entire unit being generally mobile in several degrees of freedom. The images are projected by several projection devices. These projection devices are generally of two types: 1) those related to displaying the landscape (sky and land), and 2) those displaying other aircraft, which are to have a better resolution than that provided for the landscape display.
These projecting devices are often bulky and, when they are mobile, can interfere with one another and have a high inertia which prevents them from reacting quickly and accurately, for example, to rapid movements of the user's head. Further, large angle projection devices (such as the so called "fish eye") exhibit large geometric deformations and optical aberrations. Additionally, the projection surface of the sphere, which is typically white, is by nature similar to an integrating sphere, i.e., when it is partially lit by a projector, even on a small part of its surface, no point of its surface not lit by this projector can be black. As a result, this feature of the spherical projection surface clearly reduces the contrast and therefore the perception of the resolution of the projected images.